Zero-clearance cutting systems

ABSTRACT

True zero-clearance cutting on a commercial scale is provided via a cutting area including a sacrifice material that is relatively softer than the cutter. One example is a cutting system which is capable of cutting a material such as, for example, tape or paper, into a fiber or powder. The cutting system includes a cutting blade, typically a rotary cutter, and a sacrificial plate or round bar contacting the cutting blade. The contacting portion has a zero clearance during the cutting operation. A metering mechanism is also provided which is capable of metering the material at a predetermined rate to the cutting blade. A mechanism is also provided for incrementally moving the sacrificial blade towards the cutting blade to ensure that the zero clearance is maintained between the cutting blade and the sacrificial plate, even when the sacrificial plate begins to wear down due to usage. Also, destruction of the material is further enhanced by advantageous strategic patterning of cutting edges on a rotary cutter, and further by secondary shredding features. Systems are provided for reducing to-be-destroyed paper and other relatively-thin planar materials to a dust or powder-size.

RELATED APPLICATION

Priority is claimed from a U.S. provisional application filed Dec. 26,2001, Ser. No. 60/342,111, and that application is incorporated herein.

FIELD OF THE INVENTION

The present invention generally relates to cutting systems and, moreparticularly, to cutting systems capable of reducing material to eithera shredded form or an unrecoverable fiber or powder form. Also, thepresent invention generally relates to cutting very thin materials,including very thin materials alone (such as paper, etc.) and very thinmaterials present with other components (such as a credit card, datacard, compact disk, floppy disk, cassette tape, etc.); thick materialsalso may be cut.

BACKGROUND

There are many types of cutting systems used to destroy documents andother sensitive materials. These cutting systems may include, forexample, shredders, pulverizers, grinders and other cutting systems.However, none of the currently known and used systems are capable ofcompletely destroying a document or other sensitive material into aninformation-unrecoverable form using a simple “one-step” cuttingapproach. Existing document-destruction machines are intricate, complex,and delicate. This poses a problem in high security applications, suchas highly sensitive or classified government documents that need to beeasily and efficiently destroyed for various security or businessreasons. Also, many of the known cutting systems are prone to wear,failure and other problems which require constant maintenance and/orrefurbishment. The maintenance and/or refurbishment of these complexsystems, of course, requires considerable “down-time” which, in turn,also adds to the overall costs of the system. An additional shortcomingof many of these systems is their single use nature, i.e., only capableof shredding, for instance, paper.

By way of example, U.S. Pat. No. 5,340,034 to Jang shows a papergrinder. In this system, a paper document is capable of being ground toa powder form; however, this system uses both a complex arrangementconsisting of a corrugation system and an impacting or pulverizingsystem. In this system, if one of the components fails, for example, thecorrugation system, then the document cannot be pulverized. This mayresult in a significant security risk. It is further noted that thissystem includes a complex array of rollers and cutters in order toperform the dual purpose of corrugation and pulverizing. This may leadto additional (i) component failure, (ii) maintenance and (iii)downtime, thereby increasing the cost of the entire system. Also, in thepulverizing step, it is necessary to repeatedly pulverize the materialover an extended time period in order to achieve the powder form, thusresulting in a disadvantage of the system. It is lastly noted that thissystem appears to be capable of performing its functions only on paperproducts, but not other materials which may also need to be destroyed.This is a limiting feature of the Jang apparatus.

In another example, U.S. Pat. No. 6,079,645 to Henreckson shows adesktop shredder. In this shredder, a shredding knife simply shredspaper; however, this system does not and, in fact, appears to beincapable of completely shredding paper into aninformation-unrecoverable product. Instead, the paper is merely cut intostrips. Also, this same system seems applicable only to paper products,thus limiting its applicability to other products (such as polyester(“Mylar”) tape) which require shredding or destruction. See, also U.S.Pat. No. 5,975,445 to Ko. Similarly, U.S. Pat. No. 5,320,287 to Li alsoshows a paper shredder which is provided for the limited use on paper,and which also is incapable of providing an information-unrecoverableproduct. In fact, Li only discloses that the paper may be shredded intosmaller pieces than “strip” shredders.

Of course other materials may also be destroyed for high securitypurposes. These materials may be, for example, Mylar or other thin filmsthat carry printed, punched, magnetically recorded, optically recorded,or otherwise recorded information. Such materials may also need to bedestroyed in a high security fashion. Conventionally, this couldheretofore only be is performed by high-security document“disintegrators”, which are heavy (several hundred pounds), expensive,power-hungry, and very noisy. Conventional shredding machines, including“disintegrators”, tend to jam with such materials (like Mylar), whichtend to stretch and spindle, rather than be cut properly by theshredding or “disintegrating” apparatus. As indicated athttp://www.sdiasac.com/NDSdest.doc, the U.S. National Security Agency(NSA) has evaluated certain conventional equipment as meeting, or notmeeting, the requirements for routine destruction of classified andsensitive material, including high tensile strength paper tape, papermylar-paper tape and plastic key tape as mentioned above.

Existing “high-security disintegrators” have the further disadvantage oflimited effectiveness, in that the current Department of Defensestandard for such machines specifies a 3/32″ output screen. This meansthat a particle as large as 3/32″ on a side may pass through thedisintegrator and still meet the destruction standard. In many cases, aparticle of this size may carry a considerable amount of recoverableoptical or digital information.

Such films or film-containing papers could, of course, be destroyed byincineration, but this method is undesirable for reasons of health(toxic fumes from burning), convenience, and secrecy.

Acceptable standards for high-security destruction of paper and otherproducts are being redefined to demand destruction into smaller-sizeparticles. An unmet need remains for machines, devices, methods andsystems by which to completely destroy to-be-destroyed materials, whileproviding ease, reliability and simplicity.

Scissoring is a cutting mechanism that has been conventionally appliedto paper destruction, albeit with limitations. The limitations ofconventional scissoring may be appreciated by considering a simple pairof hand-held scissors. Spring loading pushes one blade against the otherblade. The blades are not completely straight, but are intentionallycurved with a slight bow, sometimes with one blade bowed more than theother blade. As the scissors close, the structure is forcibly uncurved,which is how zero-clearance is conventionally achieved by spring loadingin scissoring technology. Initially, when the scissors are new, atcontact there are two sharp edges, which is what is wanted for cuttingaction. However, eventually the sharp edges get worn off, blunted, andground away. Eventually at the traveling point of contact, blunting andvoids in the edges occur, and clearance rather than zero-clearanceoccurs.

Certain conventional rotary shears have been attempted, to provideconventional shredders. A disk of tooled steel is notched. When thatnotched disk wipes past another part, cutting happens. However, if thereis any clearance, a to-be-cut material does not get cut, but rather,goes between the cutting edges. Such an apparatus gets dull because theaction of parts rubbing against each other wears away the material ofeach. When the parts are dull, the assembly must be taken apart and thehead replaced. Zero-tolerance between parts can be kept by usingspring-loading but such an arrangement is not actually cutting butrather is bludgeoning and takes more power than cutting.

To get a cross-cut operation, complex helical shapes are needed, andcertain shapes have been used conventionally. Helically-fluted is thebest of such conventional technology. Non-helically fluted shapes do notprovide the cross-cut, but only the strip-cut. Strip-cutting cannotreduce the output to a size as small as desired, because the there is alimit to how thin the cutters can be made, which in turn limits how thinthe resulting strips can be. Cross-cutting is needed to get smalleroutput.

A multiple-head (three-head) conventional cross-cutting destructiondevice is in use for high-security paper shredding. However, that devicehas these limitations (among others): 1) Multiple heads are needed tosequentially re-shred the material. This requires a costly and complexmachine. 2) Even with multiple heads, the shredding cutter elements mustbe tightly spaced and thin, to get small-sized output. The cuttingelements must therefore be somewhat delicate, which leads to shorteroverall cutter life, greatly reduced reliability, and greatly increasedsusceptibility to damage from the introduction of staples, paper clips,etc. into the shredding process along with the paper. This is a problemfor all high-security shredders, and the finer the output, the greaterthe problem. 3) Even with multiple heads, there is a possibility ofoversized particles getting past all of the heads.

The conventional thinking has been that, as a practical matter, theoutput can be gotten only so small, from a length x width perspective,because of design and manufacturing limitations. Namely, theconventional three-head device used two fluted rotating, meshingcylindrical parts with scissoring action, with a precision fitestablished between scissoring parts. Strips with length and widthdimensions are the output of the operation of the two fluted rotating,meshing cylindrical parts. The strip is then permitted to drop down,into a second set of the same arrangement of two fluted rotating,meshing cylindrical parts with scissoring action. Such conventionalscissoring action, multi-head machines suffer from inherent limitationsboth through machining tolerances and through the impossibility, at acertain point even if a smaller parts can be made, of providing supportfor the reduced-size parts, and providing force to shred the paperwithout bending or breaking the delicate shredder parts.

Adding to the concerns and problems discussed above for paper andpaper-like products, there is further considered the problems, perhapseven more technically complex, of destroying information stored on or inother media besides paper. For example, there is a need to be able tocompletely, reliably and easily destroy other kinds ofinformation-bearing media, such as photographs, photo negatives, compactdisks, credit cards, data cards, so-called “smart” cards (containingelectronic data storage circuits as well as magnetic and optical data),plastic film, cassette tapes, magnetic tape, etc.

SUMMARY OF THE INVENTION

The present invention is directed to overcoming one or more of theproblems as set forth above. The present inventor has found thatzero-clearance cutting is provided in an arrangement in which amaterial-to-be-cut is disposed between a relatively hard cutter materialand a relatively soft sacrifice material. The present invention exploitsuse of a relatively soft sacrifice material in conjunction with a cutteror cutting system.

In another preferred embodiment, the invention provides a method ofreducing a to-be-destroyed material to very small particles, comprising:subjecting the to-be-destroyed material to zero-clearance cuttingincluding a sacrifice system.

In another preferred embodiment, the invention provides zero-clearancecutting, by a cutting area including at least one cutting edge and atleast one sacrifice material. Advantageously, the zero-clearance cuttingmay (but is not required to) be on a commercial-scale, i.e., may includecutting repetitions on the order of thousands, tens of thousands,hundreds of thousands, even millions, without dulling of the cuttingedge. A particularly preferred example of a commercial-scalezero-clearance cutting system comprises: a cutting area including atleast one cutting edge (wherein the at least one cutting edge issuitable for cutting a material-to-be-cut) and at least one sacrificematerial (wherein the at least one sacrifice material is relativelysofter than the at least one cutting edge), with the at least onecutting edge and the at least one sacrifice material arranged to receivetherebetween a material-to-be-cut.

Any one or more of the following may be adjusted: a material of acutting edge, a size of a cutting edge or edges, a pattern of aplurality of cutting edges, a manner of movement of the cutting edge oredges, a shape of the sacrificial material, a disposition and/ormovement of the sacrificial material, and/or a feed of thematerial-to-be-cut. By such adjustments, to-be-destroyed materials maybe cut into smaller pieces in many different piece patterns, with a mostpreferred example being cutting to-be-destroyed materials (such aspaper, key-tape, photographs, credit cards, data cards, ATM cards, Smartcards, data chips, data-chip containing materials, compact disks, floppydisks, cassette tapes, etc.) into small pieces passing securitystandards and from which data cannot be recovered. Zero-clearancecutting according to the invention is particularly useful andadvantageous where some relatively thin layer to be destroyed, whetherthe relatively thin layer is alone or in conjunction with another layer(such as a thick layer, e.g., a laminate).

In a particularly preferred embodiment, the invention generally providesrotating cutter systems in which the cutter includes many small cuttingedges that respectively take tiny “nibbles” out of the to-be-destroyedplanar material, with the axis about which the cutter rotates beingparallel to the to-be-destroyed material. The cutter preferably rotatesabout a fixed axis of rotation, which axis preferably is itselfgenerally non-moving. The cutter is generally configured so that ato-be-destroyed material, once first-cut by the rotating cutter, may befurther cut and multiply re-cut by the raised cutting edges of therotating cutter (preferred examples of which cutter are a cutter withraised cutting edge patterning in a cross-cut pattern or other strategicpattern). The initial cutting interaction generally occurs with theto-be-destroyed material tightly sheared between the rotating cutteredges and at least one solid sacrificial plate or blade or rod that isof a relatively-softer material than the cutter. The to-be-destroyedmaterial is controllably fed into this tight shearing sandwich ofsacrifice material/to-be-destroyed-material/rotating cutter.

The invention also provides cutting action comprising rotary scissoring,where one “blade” of the scissors rotates, and the other “blade” is astationary sacrifice material. A to-be-destroyed material is fed(preferably controllably fed) between the respective rotating blade andsacrifice blade, preferably with continued rotary scissoring until theto-be-destroyed material has been destroyed (such as wherein theto-be-destroyed material has been converted into a security-level finematerial).

Another embodiment provided by the present invention is that of a rotaryscissors device comprising a first scissors blade and a second scissorsblade, wherein the first scissors blade rotates and the second scissorsblade is stationary, the stationary blade comprising a stationarysacrifice material that is relatively softer than the rotating blade.Such a rotary scissors device preferably includes a feeder receiving ato-be-destroyed material and providing the to-be-destroyed materialbetween the respective rotating blade and sacrifice blade. Preferablysuch a feed is controllably metered. Preferably such a feederaccommodates paper. Preferably the rotary scissors device in continuedoperation provides zero-clearance yet does not suffer significant bladeblunting or dulling that affects cutting due to the zero-clearance. In amost preferred embodiment, the inventive rotary scissors device's outputis a security-level fine material.

Where the invention provides rotary scissoring or a rotary scissorsdevice, preferably the rotating blade preferably is serrated. The tworespective scissors blades are in zero-clearance oressentially-zero-clearance shearing contact with each other.

In yet another embodiment, the invention provides a method of destroyinga to-be-destroyed planar material, comprising: passing theto-be-destroyed planar material through a rotating cutter system,wherein the cutter includes a plurality of cutting edges thatrespectively take tiny nibbles out of the to-be-destroyed planarmaterial, with the axis about which the cutter rotates being parallel tothe to-be-destroyed planar material. In such a method, preferably thecutter rotates about a fixed axis of rotation; and/or the cutterrotation axis is itself generally non-moving. In most preferredembodiments, preferably the method includes initial cutting of theto-be-destroyed material by at least one cutting edge of the rotatingcutter, followed by further cutting by at least one other cutting edgeof the rotating cutter; and/or comprises multiple further cutting;and/or the cutting edges of the rotating cutter are arranged in astrategic pattern.

The present invention in another embodiment provides a cutting systemcomprising shearing a to-be-destroyed planar material between (1) cutteredges provided on a rotating cutter and (2) at least one solidsacrificial material that is of a relatively-softer material than thecutter edges. Such a cutting system preferably includes a tight shearingsandwich of sacrifice material/to-be-destroyed-material/rotating cutter(and, in a further preferred embodiment, the to-be-destroyed-material iscontrollably fed into the tight shearing sandwich). The tight shearingsandwich is zero-clearance or essentially zero-clearance. Preferably,the cutter is cowled (most preferably, further including a secondarycowling). Preferably, the cutting system includes auger action fortransporting initially-cut to-be-destroyed material.

In one aspect of the present invention, a cutting mechanism fordisintegrating a material is provided. The cutting mechanism includes amechanism for feeding the material at a predetermined,positively-controlled rate and at least one cutter (such as a rotarycutter) positioned downstream from the feeding mechanism. In theparticularly preferred example of a rotary cutter, the edge of at leastone sacrificial plate, preferably of softer material than the cutter,just barely contacts a portion of the rotary cutter during a phase ofrotation of the rotary cutter. The contacting zone is a zero clearanceportion between a portion of the rotary cutter and the sacrificialplate. The material is metered to the zero clearance zone by themetering mechanism for disintegrating the material into a fiber orpowder form. A “sacrificial plate” and “sacrificial blade” are mentionedas shapes of sacrificial material according to the invention. Othershapes for sacrificial material in the invention may be used, such as,e.g., a round bar.

In another aspect of the present invention, the cutting mechanismincludes a guiding mechanism and a metering mechanism downstream of, andin line with the guiding mechanism. A cutting mechanism having a zeroclearance zone is also provided. The cutting mechanism includes acutting blade array disposed concentrically about a shaft and at leastone sacrificial plate or round bar having an arc zone conforming to ashape of the cutting blade. The zero clearance zone is disposed betweenat least a cutting portion of the cutting blade and the sacrificialplate or round bar.

In still further embodiments, a cutting mechanism includes a positivelycontrolled feeding mechanism and a cutting mechanism having a zeroclearance portion formed therebetween. The cutting mechanism includes acutting blade disposed concentrically about a shaft and at least onerotatable sacrificial rod having an initial cutout portion. The zeroclearance portion is disposed between at least a cutting portion of thecutting blade and the rotatable sacrificial rod.

In further embodiments, a method of destroying polyester material, paperor other material is provided. In these methods, for example, thepolyester material is fed at a predetermined positively controlled ratetowards a zero clearance portion formed between a cutter and at leastone sacrificial blade or round bar. The polyester material is grabbed bya tooth of the cutter and pulled into the zero clearance portion withthe tooth of the cutter. The polyester material is then sheared and/orcrushed between the cutter and the sacrificial blade or round bar at thezero clearance portion. This same method can be used for material orother product, and the feeding rate may vary.

One preferred embodiment of the invention provides a zero clearancecutting apparatus, comprising: at least one cutter; andpositively-controlled material feed mechanism for controlling a feedingrate of material to be destroyed; and at least one sacrificial blade orround bar abutting a portion of the at least one cutter during arotation of the at least one cutter, the sacrificial blade or round barbeing relatively softer than the cutter.

Another preferred embodiment of the invention provides a cuttingmechanism for cutting a material, comprising: a metering mechanism forfeeding in the material at a predetermined, positively controlled rate;a rotary cutter positioned downstream from the metering mechanism; andat least one sacrificial blade or round bar which contacts a portion ofthe rotary cutter during a phase of rotation of the rotary cutter, thecontacting portion being a zero clearance portion between a portion ofthe rotary cutter and the sacrificial blade or round bar, wherein thematerial is metered to the zero clearance portion by the meteringmechanism for disintegrating the material into a fiber or powder form.

The invention in a further preferred embodiment provides a cuttingmechanism, comprising: a guiding mechanism; a metering mechanismdownstream and in line with the guiding mechanism; and a cuttingmechanism having a zero clearance portion, the cutting mechanismincluding: a cutting blade disposed concentrically about a shaft; and atleast one sacrificial plate or round bar having an arc portionconforming to a shape of the cutting blade, the zero clearance portionbeing disposed between at least a cutting portion of the cutting bladeand the sacrificial plate or round bar.

Another preferred embodiment of the invention provides a cuttingmechanism, comprising: a positively controlled feeding mechanism; and acutting mechanism having a zero clearance portion, the cutting mechanismincluding: a cutting blade disposed concentrically about a shaft; and atleast one rotatable sacrificial rod having an initial cutout portion,the zero clearance portion being disposed between at least a cuttingportion of the cutting blade and the rotatable sacrificial rod.

Additionally, the invention in a preferred embodiment provides apositively controlled feeding mechanism, comprising: a first side platehaving a vertical slot and an opening; a second opposing side platehaving a vertical slot and an opening; a driven capstan mechanismpositioned between the first side plate and the second opposing sideplate; and a roller mechanism having a roller shaft, the roller shaftbeing captured within the vertical slot of the first side plate and thevertical slot of the second opposing side plate, the roller shaftfurther being positionable relative to the opening of the first sideplate and the opening of the second side plate for removal thereof.

In another preferred embodiment, the invention provides a method ofdestroying polyester material, comprising the steps of: feeding thepolyester material at a predetermined positively controlled rate towardsa zero clearance portion formed between a cutter and at least onesacrificial blade or round bar; grabbing the polyester material with atooth of the cutter; pulling the polyester material into the zeroclearance portion with the tooth of the cutter; and disposing thepolyester material between the cutter and the sacrificial blade or roundbar at the zero clearance portion.

An additional preferred embodiment of the invention provides a method ofdestroying paper, comprising the steps of: feeding the paper at apredetermined positively controlled rate towards a zero clearanceportion formed between a cutter and at least one sacrificial blade orround bar; grabbing the paper with a tooth of the cutter; pulling thepaper into the zero clearance portion with the tooth of the cutter; anddisposing the paper between the cutter and the sacrificial blade orround bar at the zero clearance portion.

The invention also provides, in a preferred embodiment, a method ofdestroying a material, comprising the steps of: feeding the material ata predetermined positively controlled rate towards a zero clearanceportion formed between a cutter and at least one sacrificial blade orround bar; grabbing the material with a tooth of the cutter; pulling thematerial into the zero clearance portion with the tooth of the cutter;and disposing the material between the cutter and the sacrificial bladeor round bar at the zero clearance portion.

Additionally, in another preferred embodiment, the invention provides amethod of protecting a cutter longevity and/or achieving zero-clearancecutting, comprising: sacrificing at least one solid blade bed or roundbar against a cutter, wherein the blade bed is (a) relatively softerthan the cutter and (b) relatively harder than an object or a materialbeing destroyed by the cutter.

In the inventive apparatuses, mechanisms, methods, systems and products,the following are mentioned as preferred perfecting details and not aslimitations on practicing the invention. With regard to the at least onecutter, a rotary cutter is mentioned as an example that may be used. Thecutter may destroy a to-be-destroyed object by such preferabledestruction as cutting, grinding, slicing, crushing, chopping and/orshredding.

The positively-controlled material feed mechanism may control particlesize of the material being destroyed by controlling both (a) the feedrate of the material entering between the at least one sacrificial bladeor round bar and the at least one cutter and (b) the rotational speed ofthe at least one cutter.

The output may be one of an information-unrecoverable product or ashredded product, and a disintegrated product.

The sacrificial blade may be one of a plate and a rotatable rod. Therotary cutter may be made from a first material and the sacrificialblade or round bar may be made from a second material which is softerthan the first material (such as the first material being one of steeland carbide and the second material being aluminum). The sacrificialblade or round bar may include an edge (such as an arc shaped edge)which conforms to a shape of the path of the rotary cutter at thecontacting portion. A mechanism may be included for incrementally movingthe sacrificial blade or round bar into contact with the rotary cutteras the sacrificial blade or round bar wears down. The incrementallymoving mechanism may be a rotating jackscrew mechanism coupled to thesacrificial blade or round bar. The jackscrew may include an outwardextending plate or screw-tapped-plate which is adapted to lift thesacrificial blade or round bar into contact with the rotary cutter.There may be included a motor for driving the rotary cutter, themetering mechanism and the rotation of the jackscrew; and/or a gearreduction system between the motor and the jackscrew. The meteringmechanism may include a pressure roller and a friction feed capstan.Also, with regard to the two rollers, one or both may be driven.

When a rotary cutter is used, the arrangement may be that at least onetooth of the rotary cutter grabs the material prior to the materialbeing metered into the zero clearance portion. It may be provided forthe combination of the rotary cutter and the sacrificial blade or roundbar to cut the material into the fiber or powder form. There may beincluded a mechanism adapted to ensure the at least one sacrificialplate or round bar is in contact with the cutting blade during arotation of the cutting blade. There may be included a pressure platecontacting the sacrificial plate or round bar, the pressure plateadapted to at least maintain a position of the sacrificial plate orround bar with respect to the cutting blade and substantiallyeliminating vibrations caused during a cutting procedure. There may beincluded a mechanism coupled to the pressure plate for providingpressure to the pressure plate. The pressure plate may be of suchmaterial density and size as to provide inertial damping of vibrations,in addition to simple spring-driven pressure.

In the disposing step, to-be-destroyed material may be shred into aninformation-unrecoverable form. The feeding may be incremental. Anexample of a feeding rate is 13 feet per minute in a practicalembodiment.

In feeding the solid blade bed or round bar being sacrificed, examplesof feeding may be feeding continuously or intermittently to the cutter(such as sacrificing by continuous feeding of the solid blade bed at arate proportional to a rate of cutting and/or feeding theto-be-destroyed material or object; sacrificing by feed of the solidblade bed being sacrificed at a rate that is intermittent, adjustable,or in fixed increments, etc.).

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will be betterunderstood from the following detailed description of a preferredembodiment of the invention with reference to the drawings, in which:

FIG. 1 shows a cross sectional view of a cutting system of the presentinvention, wherein a sacrificial blade is featured;

FIG. 2 shows an embodiment of a rotary cutter according to the presentinvention;

FIG. 3 shows another embodiment of a cutting system of the presentinvention, wherein a round bar of sacrificial material is featured;

FIGS. 4A-4D show a pressure system and quick change mechanism of thepressure roller of FIGS. 1 and 3;

FIGS. 5A-5D show a to-be-destroyed material in various positions withina cutting system of FIG. 1, with a sacrifice blade being used inconjunction with a rotary cutter, with the view enlarged to show theinteraction between the material to be destroyed M, the rotary cutter,and the sacrifice blade

FIGS. 6A-6D show a to-be-destroyed material in various positions withina cutting system of FIG. 3, with a round sacrificial material being usedin conjunction with a rotary cutter, with the view enlarged to show theinteraction between the material to be destroyed M, the rotary cutter,and the sacrifice material.

FIGS. 7-8 show exemplary reciprocal cutter systems according to theinvention, with FIG. 7 showing an exemplary inventive embodiment inwhich a sacrificial blade is diagonally-fed towards a shearing blade andFIG. 8 showing an exemplary inventive embodiment in which a to-be-cutmaterial is diagonally-fed and a round sacrifice material is used with ashearing blade.

FIG. 9 shows an exemplary inventive embodiment in which more than onesacrifice material is used.

FIGS. 10A-10C show conceptual diagrams according to the presentinvention, in which a to-be-cut material M is cut.

FIG. 11 shows, close-up, an embodiment of a cutting mechanism that isespecially preferred for destroying standard 8½ inch wide paper, withthe close-up view particularly showing that the leading edges of theserrations are laterally offset slightly.

FIGS. 12A-12D are views of an exemplary paper destruction deviceaccording to the invention. FIG. 12A is a side view (with stator 600(see FIG. 12B) removed) of an exemplary paper destruction device. FIG.12B shows the removed stator corresponding to FIG. 12A. FIG. 12C is apaper-feed view. FIG. 12D is a top view, showing an exemplaryarrangement in a paper-destruction system, of an inventive primarycutter and secondary shredder.

FIG. 13 is a flow-chart according to an inventive embodiment in whichsize of cut pieces is taken into account.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In an important aspect, the invention provides zero-clearance cutting,by a cutting area including at least one cutting edge and at least onesacrifice material. It will be appreciated that at least one cuttingedge is selected with regard to the material or materials desired to becut, i.e., the cutting edge should be suitable for cutting the materialor materials desired to be cut. The sacrifice material is selected withregard to the material of the cutting edge, namely, the sacrificematerial must be relatively softer than the at least one cutting edge. Asuitable sacrifice material should be firm enough to provide support sothat a to-be-destroyed material is properly sheared and/or cut, and yetpreferably should be no harder than necessary. Excessive hardness of asacrifice material is avoided so as not to wear the cutting edge thatcontacts the sacrifice material more than necessary. Generally, a pairof a cutter material and a respective sacrifice material is selectedbased on the characteristics of the to-be-destroyed material.Preferably, the sacrifice material is selected so that the wearcomponent due to the sacrifice material is trivial compared to the wearcomponent due to the to-be-destroyed material.

Paper is a common material sought to be destroyed. Paper can begenerally very abrasive, and tends to wear out a cutting blade appliedto paper. Typically, a hardened steel (coated or uncoated) cutter isused for cutting paper. Preferred examples of a sacrifice material touse with a typical machined, hardened steel (coated or uncoated) cutterinclude, for example, common aluminum (with most preferred examplesbeing Alloys 6063, 3003, 5052, etc.), etc. When a harder cutter materialis used (such as, e.g., diamond or carbide), the desirable sacrificialmaterial is still, of course, relatively softer than the cutter, but thesacrifice material will be particularly selected based both on thecutter material and on the thing being cut.

By so pairing a relatively-softer sacrifice material with a hard cuttingedge, repetitions of zero-clearance cutting advantageously may beachieved on a commercial scale, i.e., may include cutting repetitions onthe order of thousands, tens of thousands, hundreds of thousands, evenmillions, without significant dulling of the cutting edge due to thesacrifice material. Of course, optionally, non-commercial orfewer-repetition zero-clearance cutting operations also may be providedby the invention.

Reference is made to FIGS. 10A-10C, which are a conceptual depiction, inwhich the arrows for C_(H) and S_(s) conceptually mean the general useof a relatively hard cutting system and a relatively soft sacrificematerial. Referring to FIG. 10A, it will be appreciated that at aninitial time before a to-be-destroyed material M enters a cutting systemused with a sacrificial material, there exists a gap between into whichthe to-be-destroyed material M can be inserted. As the material Mtravels through the gap between the cutting system C_(H) and thesacrificial material S_(s) the cutting system C_(H) and/or thesacrificial material S_(s) are operated so that the gap is only open fora relatively short time and that only a small part M′ of material Mpasses before zero-clearance is forcibly established. Zero-clearancehaving been forcibly established so that original material M isseparated into still-advancing piece M′ and piece M″ which has passedthrough the cutting area, piece M″ then travels separately from pieceM′. The process of FIGS. 10A-10C is repeated for M′. It will beappreciated that C_(H) and S_(s) are conceptual and do not necessarilyrepresent a single cutter or cutting edge or a single sacrificialmaterial. For example, advancing material M may encounter a firstcutting edge, then, reduced to M′, may encounter a second cutting edge,etc. It further will be appreciated that M″ in FIG. 10C may be subjectedto further processing (such as further cutting).

A particularly preferred example of a commercial-scale zero-clearancecutting system comprises: a cutting area including at least one cuttingedge and at least one sacrifice material, with the at least one cuttingedge and the at least one sacrifice material arranged to receivetherebetween a material-to-be-cut. In mechanically arranging any cuttingedges and sacrifice material used, there is taken into account theto-be-cut material, including the width, length, thickness, and overallcomposition of the to-be-cut material. The cutting edge(s) and sacrificematerial are arranged so that the to-be-cut material is disposed in anopening between a cutting edge and the sacrifice material, and thatcutting may occur with the cutting edge extending entirely through theto-be-cut material to directly contact the sacrifice material, resultingin a piece of the to-be-cut material separating from the to-be-cutmaterial.

Any one or more of the following may be adjusted: a material of acutting edge, a size of a cutting edge or edges, a pattern of aplurality of cutting edges, a manner of movement of the cutting edge oredges, a shape of the sacrificial material, a disposition and/ormovement of the sacrificial material, and/or a feed of thematerial-to-be-cut. By such adjustments, to-be-destroyed materials maybe cut into smaller pieces in many different piece patterns, with a mostpreferred example being cutting to-be-destroyed materials (such aspaper, key-tape, photographs, credit cards, data cards, compact disks,floppy disks, cassette tapes, etc.) into small pieces passing securitystandards and from which data cannot be recovered.

The zero-clearance cutting of the invention may be used in differentways, with a preferred example of use of zero-clearance cutting beingcutting to achieve an output no bigger than a certain predeterminedtarget size (such as an output meeting industry security standards, anoutput from which no data is recoverable, an output that is satisfyinglysmall from a naked eye visual perspective, etc.). A general embodimentof such a use of zero-clearance cutting to achieve an output no biggerthan a predetermined target size may be appreciated with regard to FIG.13, showing a zero-clearance cutting system with size-sensitivity as tothe cut pieces. A to-be-destroyed material M is disposed (900) in acutting area including a sacrifice material, whereby piece(s) arecreated (901). If the size of a piece is less than a predetermined size,the piece is permitted (903) to exit the cutting system. Such exit ofappropriately-small size pieces can be mechanically provided byproviding suitable cowling around the cutting area and adjusting size ofany egress hole(s) for the sufficiently-small size pieces. It will beappreciated that where the particles are so small as to be dust-like (asmay be achieved in a particularly preferred embodiment of theinvention), preferably a vacuum system is used to collect and remove thesmall particles.

Still referring to FIG. 13, if the size of a piece is greater than apredetermined size, the piece is subjected (902) to furthersize-reduction, and more piece(s) are created (901). It will beappreciated that the further size-reduction may be cutting including asacrifice material (in the same or different cutting area including asacrifice material), or may be cutting not involving a sacrificematerial, or may be non-cutting size-reduction. In a preferred example,there is used a rotary cutter patterned with strategically arrangedcutting edges, and a to-be-cut material is first disposed in a cuttingarea including a sacrifice material working with a first cutting edge,and then a resulting piece or pieces are next disposed in a cutting areaincluding the sacrifice material working with a second cutting edge. Inanother preferred example, zero-clearance cutting using a sacrificialmaterial is used as an initial cutting system, and too-large particlesare then further subjected to a no-sacrificial material secondaryshredder system.

A particularly preferred use of the present invention is to cut astarting material into high-security fine pieces. Examples of a startingmaterial with which the present invention is useable and which may bemade into high-security fine pieces include: paper (such as a singlesheet of paper, a stack of paper, etc.), a compact disk, key tape,magnetic tape (such as magnetic tape pulled from a cassette orcartridge, magnetic tape still within a cassette, etc.), a laminateddata-bearing card, a credit card, a bank card, stored computer-readabledata (such as in a diskette, hard disk, floppy disk, etc.).

The invention in one embodiment provides cutting action comprisingrotary scissoring, where one “blade” of the scissors rotates, and theother “blade” is a stationary sacrifice material (most preferably asacrifice material that is relatively softer than the rotating bladethat it contacts). The stationary sacrifice material may be formed inthe shape of any shape (such as a bar, etc.) that does not interferewith the cutting action of the sacrifice blade with the rotating bladewhen a to-be-destroyed material is fed between the respective rotatingblade and sacrifice blade. While in this embodiment of the invention,the general the arrangement of blades has some characteristics of areel-type lawn mower, a reel-type lawn mower design would not besuitable for precision cutting at security-level standards, for at leastseveral reasons, including the impossibility of getting thesame-hardness, non-serrated blades sufficiently close together forreliably cutting a material-to-be-destroyed. The present inventionexploits the advantages of rotary scissoring and rotary cutting, andsolves the problems (such as rapid dulling of blades) associated withbringing two same-hardness blades in contact with each other. Thepresent inventor has recognized that the contacting blades need not beof the same hardness, and preferably are not of the same hardness, andfurther has recognized advantages of using different hardness blades incutting (preferably in rotary cutting), e.g., the ability to providezero-clearance cutting action or essentially-zero-clearance cuttingaction.

An embodiment of the present invention is directed to a cuttingapparatus used to shred or cut paper, tape or other materials orproducts into a shredded, cut or information-unrecoverable,disintegrated form such as a fine fiber or powder form. In a preferredembodiment, the fine fiber or powder form makes data or image recoveryimpossible and is thus very advantageous for security and otherconfidentiality reasons. The present invention is capable of providingsuch shredded or fine fiber or powder form through a single cuttingprocess which thus minimizes component parts and maintenance issueswhile increasing efficiency and productivity. In order to provide theadvantages of the present invention, the cutting apparatus incorporatesa zero clearance cutting surface between a cutting mechanism and atleast one sacrificial blade or plate or bar. The material or product issupplied to the zero clearance portion of the apparatus of the presentinvention at a predetermined feed or metering rate via a manual feedingor, alternatively, a feeding or metering mechanism such as, for example,motor and gear-driven rollers and the like.

This invention in a particularly preferred embodiment makes use ofdistinct and deliberately determined feeds, one for the material beingcut, and the other for the gradual advancement of the sacrificialmaterial into the cutting zone. Either may be automated or manuallycontrolled.

The style of the cutter (e.g., the pattern, the teeth) is directed bythe application. For example, a helically-fluted cutter with“chip-breaker” serrations on the flutes can be implemented to: (1)create small chips of residue, and (2) capture and direct the flow ofthe residue for destroying standard 8½ inch wide paper.) The cuttingsystem in FIG. 1 is generally depicted as reference numeral 100 andincludes a housing or frame 102. A material guide 104 is mounted to theframe 102 via any conventional mechanism. The material guide 104includes a pivotally attached upper mechanism 106 a and a lowerstationary guide plate 106 b. In this arrangement, to-be-destroyedmaterial such as, for example, tape (e.g., Mylar or other polyesterfilm, etc.), paper or other product is guided to a cutting mechanism(described below) for disintegrating the to-be-destroyed material. Thematerials being fed may have information written thereon or punchedthereinto or may simply be other types of product such as produce or thelike. The arrangement of FIG. 1 can be used to destroy, otherwisedifficult to destroy products, such as the Mylar tape and otherproducts. A motor 108, of any conventional type, is mounted on the frame102. In a specific embodiment, the motor is a 300 watt motor which uses100-130 VAC or DC; however, any motor may be used including a motorcapable of using an optional back-up battery system.

Still referring to FIG. 1, a feeding mechanism 110 is provideddownstream and, in embodiments, in-line with the material guide 104. Thefeeding mechanism 110 includes a rubber pressure roller 112 and afriction feed capstan 114. The friction feed capstan 114 is preferablydriven by the motor 108 which may provide, in embodiments, apredetermined, controlled feed rate of the product at approximately 13ft/min (4 meters/min) or other rate. It should be readily recognized bythose of ordinary skill in the art that the friction feed capstan 114may provide a different metering rate by adjusting the revolutions perminute (RPM) of the friction feed capstan 114, itself. For example, thefriction feed capstan 114 may be adjusted to 120 RPM, or a lower orhigher RPM depending on the particularly desired feed rate. The feedingmechanism may also provide a very firm retardation (hold back) of theproduct being fed into the cutting mechanism. By increasing the feedrate (assuming a constant cutter rotational speed), a perforation(rather than a cutting) may be performed on the product. In embodiments,a user may also manually feed the product to the cutting mechanism.

The cutting mechanism, generally depicted as reference 116, includes arotary cutter 118 and sacrificial material in the form of a sacrificialplate 120. In the embodiments of the present secondary processing, whenused in conjunction with a suitable cowling to keep the residueparticles captivated by the flutes. Preferred examples of a cutterpattern are a rotary cross-cut or a herringbone file type of pattern. Inanother embodiment, the cutter can be like a helically-fluted millingcutter, preferably with “chip-breaker” serrations, off-set from eachother, flute-to-flute, to produce tiny chips. For a tape-destructionmachine, an exemplary cutter is one according to FIGS. 1, 2, 3, 5A-6D,with a preferred tape-destruction cutter having 24 helical teeth,interrupted by reverse-helix pattern grooves, with each helical toothspiraling across the entire cutter length, interrupted by thereverse-helix groove pattern (with the reverse-helix groove patternbeing ground on later in the manufacturing process in a preferred methodof making such a cutter). For an 8½ inch wide paper-destruction machine,a preferred cutter is one with flute-grooves (especially suited to carrythe chips to a secondary shredder section).

The invention particularly exploits the relative hardness relationshipbetween a cutter (such as, e.g., rotary cutter 118 in FIG. 1) and arelatively less-hard sacrificial material (in a shape such as, e.g.,sacrificial plate 120 or sacrificial rod 220). By way of example, thecutter may comprise tool steel, carbide or other high strength,relatively hard material. On the other hand, the sacrificial materialmay be aluminum or other relatively-soft material.

For any given cutter, the sacrifice material composition mayappropriately be varied or selected, and may be used in various shapesand compositions, and disposed in various movements and patternsrelative to a cutting edge with which the sacrifice material is desiredto contact.

The cutting systems of the present invention may be used to destroyvarious materials, including paper, key-tape, paper-like material, etc.,of various dimensions (such as various widths, such as key-tape-width,8½ inch width, etc.); compact disks; photographs; floppy disks; film;credit cards, Smart cards, magnetic tape; etc.

Referring now to FIG. 1, an overview of an exemplary cutting system ofthe present invention is shown. (FIG. 1 is the most preferred system fordestroying tape; another embodiment is set forth below with reference toother figures, as the most preferred system for invention there is azero clearance 119 zone between at least a portion of the rotary cutter118 and the sacrificial plate 120; that is, a cutting surface of therotary cutter 118 contacts the sacrificial plate 120 during the cuttingprocess. The sacrificial plate 120 includes an edge 120 a whichsubstantially conforms to the arc shape of the rotary cutter 118. Due tothe arrangement between the sacrificial plate 120 and the rotary cutter118, any product supplied to the rotary cutter 118 will be eithershredded or disintegrated to an information-unrecoverable fine fiber orpowder form by passing through the zero clearance 119 zone depending onthe particular cutter type used with the present invention.

There is a preferential geometric relation between the cutter, sacrificecontact zone, and point of material entry. Specifically,

1. Assume that the material approaches the cutting zone from the left ofthe cutter's center of rotation.

2. Drawing a line downwards vertically originating from the center ofcutter rotation, and then another line downwards (same origin) at anangle of approximately 45 degrees, biased towards the left of theorigin, the point where this line intersects the periphery of the cutteris the preferential material entry point, and also the point of contactwith the sacrifice material. This is the location identified asreference numeral 119 in FIGS. 1, 3, 5A-5D, 6A-6D.

3. This approximate position 119 is preferential because materialentering at this point will tend to be captured by the advancing cutterpoints or blades, but not tend to be dragged through thecutter/sacrifice interface any more than necessary.

It should be understood that if the material were to be fed above thispoint 119, there is less and less capturing tendency as the point ofentry is raised. If the feed point is raised above the center of thecutter, the cutter will tend to push the material away, rather than drawit in. Also, if the point of entry is lowered, there is greater andgreater tendency of the cutter to capture and drag the material throughthe cutter/sacrifice interface, which places unnecessary stress on thefeeding mechanism, whose purpose is to force the material feed at apredetermined rate (not more, and not less). In an extreme case, thecutter mechanism could drag the material through with such force as tostretch or break the material, rather than “nibble away” at it. It isthe controlled, “nibbling away” of the material by the cutter whichallows the machine to produce the superior shredding action intended.This being the case, positive control of material in-feed is essential,and achieved partly by an advantageous, appropriate geometry.

It is preferred that the rotary cutter 118 be made from a material whichis harder than the sacrificial plate 120. By way of example, the rotarycutter 118 may comprise tool steel, carbide or other high strength,relatively hard material. On the other hand, the sacrificial plate 120may be made from aluminum or other softer material. In embodiments, thesacrificial plate 120 is made from material which allows approx. 30,000feet of product to be fed through the rotary cutter 118 prior to aone-inch-length of sacrificial plate 120 completely being consumed.Similarly, the rotary cutter 118 is made from material that allows40,000 feet of paper product to be fed through the rotary cutter 118prior to the rotary cutter 118 wearing down due to usage. Polyester andother materials may cause much faster cutter wear. Of course, thesacrificial plate 120 and the rotary cutter 118 may wear down or becomeduller at other rates depending on the particular materials used to makethe sacrificial plate 120 and the rotary cutter 118 and the productbeing fed and the feed rate therethrough; however, it is preferred thatthe sacrificial plate 120 be designed to wear down much more slowly thanthe rotary cutter 118.

It should further be recognized by those of ordinary skill in the artthat the rotary cutter 118 is driven by the motor 108, and may be drivenat a different rate than the feeding mechanism 110. By adjusting thefeeding rates of the rotary cutter and the feeding mechanism 110,different types of cuts or shredding patterns may be accomplished. Also,the rotary cutter 118 may be any type of rotary cutter such as, forexample, a helical cutter, a milling cutter with helical pitches orflutes, razor blade cutting edges, a perforator, or the like. The rotarycutter 118 may additionally have various diameters such as ½ inchdiameter and should, preferably, be concentrically mounted to a shaft118 a.

The motor 108 may additionally drive a jackscrew 122 or other liftingmechanism that is designed to incrementally move the sacrificial plate120 into contact with the rotary cutter 118. This ensures that contactremains between the rotary cutter 118 and the sacrificial plate 120,even as the sacrificial plate 120 wears down due to usage. The jackscrew122, in embodiments, includes an outward extending non-rotating jacknutplate 213 which contacts a portion of the sacrificial plate 120. Thejacknut plate 213 lifts the sacrificial plate 120 as the jackscrew 122rotates, via the motor 108 (through a suitable gear train). Toincrementally move the sacrificial plate 120, via the jackscrew 122, agear reduction system 124 is provided between the motor 108 and thejackscrew 122. By way of example, a gear reduction system may revolvethe jackscrew one-half revolution/hour at a cutter speed of 15,000 RPM.

FIG. 1 further shows a pressure plate 126 and a spring plunger 128. Thepressure plate 126 is provided for two purposes: (i) ensuring that thesacrificial plate 120 is maintained in a proper position with relationto the rotary cutter 118 and (ii) minimizing or dampening the vibrationcreated by interaction of the rotary cutter 118 and the sacrificialplate 120 during the cutting process. The latter feature is provided bythe pressure provided by the spring plunger 128 and the simple inertiaof the pressure plate 126 itself. The pressure plate 126 shouldpreferably allow sliding movement of the sacrificial plate 120 towardsthe rotary cutter 118 during the operations thereof. It is noted thatthe pressure plate 126 should, however, not be in contact with therotary cutter 118, although it is deliberately positioned so as toprovide pressure and vibration dampening to the sacrifice plate in asclose a proximity as practicable to the cutting zone 119.

A vacuum source and collection bag (not shown) may also be used with thepresent invention. The vacuum source and collection bag will ensure thatno fiber or fine powder contaminates the mechanisms and surroundingarea. The vacuum source and collection bag also allow for easy clean upand the like.

The rotary cutter 118 may include many different types of cuttingpatterns, with the type of cut or shredding of the product depending onthe type of cutting blade. For example, a helical cutting blade will notcut an entire strip of the product, but will instead cut chunks ornibbles from the product. On the other hand, a straight cutting blade orarray of razor blades, for example, may cut the product into strips.This provides additional flexibility to the system of the presentinvention. A plain rotary file is not considered a preferred design,because the output might be slivers rather than chips, and the sliverstheoretically could be as long as the tape is wide (1″) which isundesirable. FIG. 2 shows an embodiment of one rotary cutter 118 usedwith the present invention and especially suited to tape destruction. InFIG. 2, the rotary cutter 118 is shown to include a concentricallymounted shaft 118 a and a rotary file style cutter with a helicalpattern 118 b. A cross-cut rotary file-type cutter pattern provides tinychips laterally (across the tape width).

-   -   (a) A cut zone follows a line drawn touching the cutter exterior        surface and parallel to the cutter shaft; moving across the tape        in the line of the cut zone, the individual teeth of the cutter        are in varying phases of engagement along the line of the cut        zone, which results in short widths of each chunk.    -   (b) The length of the resulting chip (along the tape length) is        determined by the relationship between the rotary speed of the        cutter and the speed of the tape feed into the cutter.        Individual teeth engage the tape in the cutting zone in very        rapid succession as the cutter rotates. Because only a very        small length of tape is fed into the zone for each passage of a        tooth, the resulting chips are very short.        The net result is that the chips are both short and narrow. By        arranging combinations of rotary speed and rate of feed of        to-be-destroyed material, the destruction device can be        configured to produce dust-like particles.

One successful embodiment of the cutter uses a cross-cut herring-bonepattern for the cutter surface (as shown) which could be made from acutter such as Manhattan Supply Co. part #60469665, a commerciallyavailable cross-cut rotary file. The cutter may also be made by using acommon ½″ diameter, 2-flute or 4-flute milling cutter, with its two endsground down to a diameter suitable for the bearings selected. Anordinary tool-steel twist drill could have its flutes reground and besimilarly modified for use as a cutter. In further embodiments, thecutter may also be made from an elongated spur gear of hardenedmaterial, with the external cylindrical-shaped surface ground so thatthe tooth ends are sharp, with its two ends ground down to a diametersuitable for the bearings selected. The sharpened teeth would thennibble off the to-be-shredded material trapped between the teeth and thesacrificial bed material. As to size, the cutter diameter may be about½″ but is not required to be a particular diameter, except that if thecutter is very long (e.g., 9 or more inches for full-size papershredding), it must be of sufficient diameter to be stiff enough not tobend or whip around at its middle section during high speed rotation. Itshould also be rigid enough so that its cutting surfaces stay engaged tothe sacrifice material throughout rotation.

FIG. 3 shows another embodiment of the present invention. In thisembodiment, the sacrificial material is in the form of a rotary-mountedsacrificial blade 220. That is, the sacrificial blade 220 is a rotatingsacrifice rod which is gear driven at preferably 0.01 revolutions/hour.The rod is preferably ⅜″ in diameter. Of course, other revolution ratesand diameters are also contemplated for use with the present invention.The cutting action and associated behaviors will be the same as that ofthe embodiment shown in FIG. 1. As seen in FIG. 3, a notch 220 b isprovided at the cutting surface for initial installation of thesacrifice blade 220.

FIGS. 4A-4D show a pressure system and quick change mechanism adaptedfor use with the feeding mechanism 110 and more particularly the rubberpressure roller 112 of the present invention. Beginning with FIG. 4A,side plates 130 are positioned on opposing sides of the pressure roller112. A roller shaft 112 a, positioned concentrically within the pressureroller 112, extends between the two side plates 130 and moreparticularly is captured by vertical slots 132 which are machined in theside plates 130. The slots 132 include through-holes 132 a. The rollerportion of the pressure roller 112 will freely rotate on the rollershaft 112 a via bearings or bushings affixed concentrically inside ofroller 112.

Pressure screws 134 protrude down into the slots 132 which, inconjunction with spacers 136, establish a maximum distance that rollershaft 112 a can be pushed downwards by the pressure screws 134 towardsthe capstan 114. In this manner, the rubber material of the pressureroller 112 provides a pinching of the material to be shredded againstthe capstan 114. That is, the force of the screw ends are able to travela certain distance (established by screw length and spacer thickness)which then, in turn, forces a predetermined deflection of therubber-like material of the roller 112. This provides positive controlof material feed, as established by the capstan 114 rotation, and thisalso eliminates the need for a separate spring. The deflectiondetermination is fixed by design (thickness of the spacers), butrelieves the operator from making any routine pressure adjustment. Thisprovides a significant operational advantage of simplicity.

This mechanism also eliminates the need for a separate swing-arm andassociated pivots or bearings and other hardware to mount and controland provide pressure to the roller.

As further discussed with reference to FIGS. 4B-4D, the presentconfiguration of the side plates 130 further allows for a quick changingscheme of the roller 112. Specifically, in FIG. 4B, it is shown that thepressure screws 134 are loosened and backed out part-way. The entireroller 112, together with the roller shaft 112 a is then raised (FIG.4C) to the height of the opening 132 a. Then, as seen in FIG. 4D, theroller shaft 112 a can easily be removed through (e.g., slipped through)either one of the openings 132 a of the side plates 132. The roller 112is now free to be pulled out and replaced. Reassembly takes place byreversing the disassembly order of FIGS. 4B-4D. This mechanism providesfor very fast and easy disassembly for jam clearance, inspection, rollershaft 112 a, or roller 112 replacement. It provides an irreduciblyminimal parts count, with no need for adjustment. The roller is simplyreplaced when it is worn out.

FIGS. 5A-5D show the various operational positions of theto-be-destroyed material being metered through the cutting system of theembodiment of FIG. 1. A machine according to FIGS. 1 and 5A-5D has beenparticularly useful in the example where the to-be-destroyed material ispaper/polyester tape, or polyester tape. However, other material such aspaper or the like may equally be used with the present invention.

FIG. 5A shows the to-be-destroyed material M prior to engagement betweenthe rotary cutter 118 and the sacrificial plate 120. FIG. 5B shows thematerial M being engaged by a tooth 118 c of the rotary cutter 118. Inthis manner, the material M begins to be pulled into the zero clearancezone 119 between the rotary cutter 118 and the sacrificial plate 120. InFIG. 5C, the material M is positioned within the zero clearance zone 119between the tooth 118 c of the rotary cutter 118 and the edge 120 a ofthe sacrificial plate 120. In FIG. 5D, an extremely small portion X ofthe material M is sliced off between the rotary cutter 118 and thesacrificial plate 120. The steps of FIGS. 5A through 5D are repeateduntil no further material M is available for metering to the cuttingmechanism. The material may be destroyed at various rates such as, forexample, four seconds for a segment of approximately 10 inches; however,other destruction rates may also be provided depending on the specificrotation of the cutting mechanism and the metering mechanism.

Akin to FIGS. 5A-5D in which a sacrificial plate 120 is shown, FIGS.6A-6D show a product in various positions within the cutting system whenthe sacrifice material is a sacrifice rod 220. FIG. 6A shows thematerial M prior to engagement between the rotary cutter 118 and thesacrifice rod 220. FIG. 6B shows the material M being engaged by a tooth118 c of the rotary cutter 118. In this manner, the material M begins tobe pulled into the zero clearance zone 119 between the rotary cutter 118and the sacrificial rod 220. In FIG. 6C, the material M is positionedwithin the zero clearance zone 119 between the tooth 118 c of the rotarycutter 118 and the sacrificial rod 220. In FIG. 6D, an extremely smallportion of the material M is sliced off between the rotary cutter 118and the sacrificial rod 220. The steps of FIGS. 6A-6D are repeated untilno further material M is available for metering to the cuttingmechanism.

Using the apparatus of FIGS. 1 or FIG. 3 on to be destroyed paper,polyester or other types of products advantageously provides an outputof high security material, most preferably a powder of finely grainedmaterial of a granular size. In this manner, the data previouslyrecorded in or on the disintegrated product will beinformation-unrecoverable. As should also be understood by those ofordinary skill in the art, the present invention may also increase thenumber and variety of the materials which may now be written on, printedon, punched into or the like by allowing the total destruction of suchmaterials, which was not otherwise practical. Plastic recording tapescontaining video, audio, and digital information have heretofore beenvery difficult to destroy, even with existing large, heavy, expensive,and noisy high-security disintegrators.

It should now also be understood that the sacrificial plate or rod takesthe place of, and performs the function of, a “blade bed” in aconventional cutting arrangement, such as might be found in a reel-typelawn mower, and many types of cutting machines. In the familiar exampleof the mower, the blade bed is usually of a hard material, and ismanually adjusted so as to allow the closest practicable approach of thereel blades, without actually coming into contact with the reel blades.If the blade bed were to actually contact the reel blades, either thereel blade or the blade bed edge would be quickly worn away. If there isany eccentricity in the path of even one reel blade, wear on one part orthe other would immediately result in some clearance between the reelblades and blade bed.

Now, if we imagine that the “grass” is thin polyester film, or someother very tough, thin material, one can readily see that the desiredcutting would not take place, because the material might well be thinnerthan the blade-to-bed clearance. The material would simply “slip”between blade and bed. Constant re-adjustment of the bed blade clearancewould be required, and this would result in intolerable wear to bladesand bed. By providing a suitable sacrificial blade bed with an automaticfeed (at minimal rates) of the “sacrificial” bed material, the presentinvention overcomes this difficult problem. Very thin, tough materialscan now be cut or shredded easily with this arrangement.

It will be appreciated that the invention thus provides cuttingmachines, products and methods in which true zero clearance cuttingclearance is effectively achieved. Cutting machines heretofore had someclearance between blades or between blades and beds. For example,scissors use spring tension to cause a wiping action between blades, butbecause scissors blades are BOTH hard materials, a mechanical, automatedscissors would dull or wear rather quickly. The present invention solvesthat problem with mechanical, automated scissors.

In operation of a cutting system according to the invention, aparticularly preferred rate for feeding sacrifice material isapproximately 30 millionths of an inch of sacrifice material per footlength of destroyed material (in the case of a sacrificial bladematerial) and a feeding rate of approximately 30 micro-inches ofsacrifice material per foot length of destroyed material, or about400,000 inches of destroyed material per inch of sacrifice material (inthe case of round sacrifice bar, see also Example 2 below).

Additionally, the invention may be applied regarding a non-rotarycutter. A scheme according to the invention may be adapted for use witha scissors-like, reciprocating, or guillotine-like cutter. An ordinaryoffice-type hand-operated paper cutter may be modified so that insteadof the usual hardened-steel stationary bed blade, the bed blade is of asacrifice material, with a mechanism to advance the sacrifice materialin minute increments.

Above, a round bar has been mentioned, and a round bar is thought theeasiest implementation. Instead of a round bar, a flexible materialincrementally fed from a roll may be used.

It will be appreciated that the invention may be used for destruction ofto-be-destroyed materials of various dimensions. When theto-be-destroyed material is key tape, or of key tape width, a preferredexample of a destruction machine is that of Example 1 below. When theto-be-destroyed material is paper of standard 8½ inch width, a preferredexample of a destruction machine is that of Example 3 below, in which a9 inch wide sacrificial plate is used. The sacrificial plate or bladesize may be adjusted to the width of the to-be-destroyed product. For arelatively wide to-be-destroyed product, appropriate engineeringconsiderations may be made to account for the relative width, such asjacking up the sacrifice plate at two points.

A particularly preferred embodiment of the present invention is adestruction machine for to-be-destroyed 8½ inch-wide paper. Aparticularly preferred embodiment of such a destruction machine for 8½inch wide paper may be appreciated with reference to FIG. 12A.

For a destruction machine particularly suited for 8½ inch wide paper,the cutter used should be relatively harder than the sacrifice material.Particularly preferred is a cutter made from cobalt steel, coated withtitanium nitrate (to enhance its hardness).

The cutter for use in destroying 8½ inch wide paper should bestrategically patterned with raised cutting edges (with serrated cuttingedges being preferred, and strategic patterning as in FIGS. 11, 12C and12D being most preferred). A basic principle according to the invention,namely, the use of a plurality of small edges that take tiny nibbles ofthe to-be-destroyed material, is used. Preferably, a cutter withvertical serrations is used. Most preferably, a small lateral or axialoffset distance (such as 7/1000 inch (0.007 inch)) is provided for thevertical serrations, as shown as offset 800 on FIG. 11. The preferredpattern resembles what in the machining trade is called “chip breakers.”The preferred small-offset design is particularly helpful in cutting thelast strip of paper or to-be-destroyed material, which, when thelength-wise material reaches the end of its travel into the machine, hasnothing controlling its travel path. Also, preferably the entire cutterassembly is cowled (enclosed in a close-fitting cylindricalconstruction).

Referring to FIG. 11, a close-up view of a rotary cutter 318 withcutting edges 318 a suitable for use in destroying 8½ inch wide paper,the strategic patterning of a rotary cutter may be further appreciated.A tiny horizontal offset 800 between leading edges of serration teeth,the offset occurring between successive flutes, is shown. The tinyserration teeth successively bite off minute chunks width-wise due tothe offset 800, as the cutter 318 rotates. The serration teeth andflutes successively bite off minute chunks length-wise due to therelationship between the rate of material feed and cutter 318 (FIG. 12A)rotation speed (number of flutes passing per unit length of fedmaterial).

The sacrifice plate for use in destroying 8½ inch wide paper is widerthan 8½ inches, preferably 9 inches or more wide to facilitate documentloading. More generally, referring to all embodiments of the invention,it will be appreciated that the width of the sacrifice plate is adjustedto the width of the to-be-destroyed item. In the case of the 8½ inchwide paper, requiring a sacrifice plate at least slightly wider than 8½inches, and that width being relatively wide for engineeringconsiderations, the sacrifice plate preferably is supported at more thanone point, such as at two points for the device of FIG. 12A. Bysynchronously driving the jackscrews 322 in FIG. 12A, the jacknuts 399can advantageously advance the sacrifice plate 320 upwards in an evenand level fashion, thus promoting uniform contact between the upwardedge of the sacrifice plate 320 and the cutting edges.

With reference to FIGS. 11 and 12A, cutting of the to-be-destroyed paperoccurs between the cutter edges 318 a and the sacrifice plate 320.Preferably, augering (screw conveyer) techniques are used and applied(and preferably used and applied repeatedly) to particles of cutto-be-destroyed material (such as cut paper). Augering is a well-knownmaterial conveying technique and is particularly useful in thishigh-security destruction application. For example, most preferably, a45 degree helical design is considered optimal for moving the cutparticles laterally. Referring to the cutter of FIG. 11 and thedestruction machine of FIGS. 12A-12D, a cut particle is urged in alateral direction by the helical design. Lateral movement of theparticles and the promotion of re-cutting and multiple re-cutting areapplied to accomplish ultimate cutting into fine, powdery particles.

Thus, destruction of the end strip of paper fed into the destructionmachine is addressed by the cowling feature and by a secondary shredder370 (see FIGS. 12C-12D). By action of the rotating cutter, all of thecut particles get flung outward at the same rate. A relatively bigparticle flung outwards will get re-chopped at the sacrifice plate 320(which presents a sharp edge). All particles are captured by thecowling, and no particle can exit radially. The only way for a particleof to-be-destroyed material to leave is axially, by way of a pluralityof holes in the stator walls of the secondary shredder (also called acomminuter) 370.

The secondary shredder's rotating cutter segment 370 uses the samegeneral fluted and serrated design as in the primary cutter 380, withgrooves (preferably such as 2/10 inch (0.2 inch) grooves). The groovesize is selected for proper clearance between the drilled stator wallsand the sides of the cutting flutes. Upon entering a side hole, anentering particle is sheared between the stator wall and the side of acutter flute as it tries to go through the side hole. Multiple choppingof a particles that enter the side hole is provided, with 10 being asuitable number of chopping times, but the number of chopping times notbeing required to be 10. Each hole in the stator wall provides twoshearing edges, one on each side of the wall. Since the cutter hasmultiple flutes, each hole, in combination with the multiplicity offlutes, can do a great deal of rapid shearing. Further, since eachstator wall has a multiplicity of holes, and is engaged successively bya multiplicity of rotating flute side-edges, the Secondary Shredderassembly has a large capacity to do the shearing job in a very smallphysical space.

Clearances preferably are not greater than 0.002 inch between the rotor(blade) and the stator walls, due to practical machining tolerances. Thesecondary shredder 370 shown in FIGS. 12C-12D has no sacrifice plate,therefore it does not provide the zero-clearance feature. Rather,clearances as close to zero as practicable are utilized, and both statorand cutter are of similar hardness.

For designing the holes and the cutting edges that will be applied to aparticle that travels through the holes, a preferred arrangement is asfollows. The holes go straight through. The strategic pattern of thecutting edges and flutes on the secondary shredder 370 is such that,from the perspective of a particle, one cannot see straight through,without seeing one or more blades blocking the path through.

Preferably, vacuum technology is applied so that a particle that hastraveled through the secondary shredder 370 is sucked out by vacuumsuction. Centrifugal force drives particles outward, and augering (screwconveyer action) drives particles sideways; vacuum application furthersthose objectives. Because dust is being made, a vacuum should be usedanyway to collect and dispose of the dust. By the configurationaccording to FIGS. 12C-12D, positive air pressure is generated by thecutter geometry and rotation because, as with a screw compressor, theparticles and air are accelerated sideways as well as radially. It willbe appreciated that, although FIG. 12A implies a standard desktop devicewith paper fed parallel to a desk surface, a destruction device also maybe configured so that paper is fed vertically (i.e., perpendicular to adesk surface), or in some other feed configuration. Vertical feeding maybe preferable because any particles that bounce out as a result of theviolence of the shredding action will fall and be sucked back in.

Thus, a rotary cutter with cutting edges in a strategic pattern, arelatively-softer sacrifice material in zero-clearance disposition tothe cutting edges, cowling technology and augering technology may becombined to achieve destruction of information-bearing paper (such asstandard 8½ inch wide paper) and paper-like materials into fine, powderyparticles of high-security size (i.e., smaller than U.S. NationalSecurity Agency (NSA)'s newly promulgated in 2002 smaller-sizedestruction requirements). It is believed that, before the presentinvention, a commercially practical technique was not known for reliablyconverting paper and paper-like materials into such fine, powderyparticles, and only into such fine particles, leaving no undestroyedmaterial. The nearest approximation would have been a “disintegrator”,which operates very differently, is much, much larger, and can onlyguarantee fine-particle output if fitted with a very fine screen. Such afine screen greatly reduce the rate of material processing, so much asto make the machine impractical.

The cutter and relatively-softer sacrifice material, and strategicaugering and cowling and Secondary Shredder having been thus mentionedabove, the following further engineering details are mentioned foradvantageously achieving high security destruction of 8½ inch widepaper, but are not necessarily required exactly as shown in theaccompanying figures in a destruction machine.

Referring to FIG. 12A, material guide 304 guides the to-be-destroyedmaterial M (such as paper). Pressure rollers 312 are disposed below andabove the to-be-destroyed material M, applying spring pressure tosqueeze the to-be-destroyed material M to provide exact metering (exactmetering being important). The 9-inch wide sacrifice plate 320 (made ofa material relatively softer than the cutter) is supported by a bolsterblock 305. The sacrifice plate 320 can be incrementally moved intocontact with the cutter (i.e., with the cutting edges of the cutter) bya jacknut 399, which moves the sacrifice plate at a slow rate, forgradually using up the sacrifice plate. The jacknut 399 pushes thesacrifice plate 320 upwards. A fixed clamp bar 397 pushes against thebolster block 305, with the pushing being accomplished by springplungers 396 mounted within clamp bar 397. The sacrifice plate 320 iseventually resisted by the static block 398. The static block 398provides the location and support for the sacrifice bar 320. The staticblock 398, bolster block 305, springs, spring plunger, and the fixedclamp bar 397 operate together to constrain the sacrifice bar to onlymove vertically. A tight sliding fit is provided for the sacrifice bar.The sacrifice bar 320 is slidably supported by the static block 398.

As seen on FIG. 12A, starting with the cutting zone on the rotary cutter318 and proceeding 360 degrees counterclockwise, the cowling around thecutter may be appreciated as follows. For about the region from 0 to 45degrees, the cowling is provided by the sacrifice bar 320 and the firsthalf of the bolster block 305. For about the next 90 degrees, stillmoving counterclockwise, the cowling is provided by the second half ofthe clamp bar 397, together with all of the fixed clamp bar 397. Thefinal 180 degrees, moving counterclockwise along the rotary cutter 318,is provided by the cowling 395. The amount left on the cutter 318,namely, about 45 degrees, is the opening, where to-be-destroyed materialM enters. This zone is largely blocked by the feed rollers 312, so thatany particles flung out by the cutter 318 will tend to rebound back into the cutter and cowled space. Note also that there must be an openingfor air to enter, in order for the vacuum to entrain cut particles andcarry then through the cutter system for collection. The air-space gapbetween the interior surface of the cowling and the exterior surface ofthe cutter 318 is relatively small, with the cowling being quite tightlyfitting around the cutter 318, while of course not touching the cutter318 in operation. The tight cowling fit is desired to keepto-be-destroyed material in the cutting system and to keep theto-be-destroyed material and pieces thereof moving.

Referring to FIG. 12A, the static block 398 supports the sacrifice plate320. The cowl reaches all the way across axially and covers 180 degrees.The cowl is a half-moon shape, for the full 9 inch length. Attachment isby bolting to a plate (not seen in the figure), with bolting only on thetop of one side. This allows for rapid and easy removal of the cowlingfor inspection, cleaning, and maintenance.

An approximately 45 degree open gap is provided, from about the 90degree point, down to the paper, so that the paper can enter. An almostcomplete enclosure “tube” is thus provided as considerable blocking isprovided by the rollers immediately adjacent.

Importantly, a significant advantage of the inventive system ismechanical simplicity. The Secondary Shredder cutter array is merely anadditional section grooved into one end of the cutter 380. A suitablestator assembly 600 (made in two halves) is simply bolted around one endof the rotating cutter, with apertures suitable for exhaust of theparticles by a simple vacuum. This is very different from conventionalshredders using multiple heads.

Referring to FIG. 12A, vacuum air entry is shown by small arrows betweenthe pressure roller 312 and rotary cutter 318. The vacuum aspects, andother aspects, of an exemplary system according to the invention may befurther appreciated with respect to the paper-feed view of FIG. 12C,from which we can see particle motion from combined action of: augeringby cutter flutes, centrifugal force, and vacuum air flow. Rotation isdepicted on the figure, with the top of the cutter rotating towards theviewer. A vacuum plenum 390 is shown, and a vacuum residue collectionsystem 389. The part of the rotary cutter 318 that is the primary rotarycutter is shown as primary cutter 380 on FIGS. 12C-12D; the part of therotary cutter 318 that is the Secondary Shredder is shown as secondaryshredder 370 on FIGS. 12C-12D.

Referring FIG. 12A, and an example in which the to-be-destroyed materialis paper, the destruction operation will be further appreciated asfollows. As the paper advances into the device, the paper undergoes acut and drag process. If the rotary cutter 318 is fast enough, themotion of the paper is trivial. Depending on the cutter motion andspeed, and on the paper feed, a certain bite pattern on the paperresults. A non-serrated cutter would give a slice. A serrated cutter isneeded to get the tiny nibbles rather than the less-desirable largerslice. (A serrated cutter also is called a “chip-breaker” cutter, alsocalled a “roughing end mill”, generally use for initial, rough-cuttingwork on metals.)

Destruction devices according to FIGS. 12A-12D advantageously take intoaccount possible clogging, by providing for unclogging by simple cowlingremoval, whereupon blowing and vacuuming can be performed.

A wire keeper (not shown on FIG. 12A) optionally may be disposed toprevent to-be-destroyed paper (such as flimsy older facsimile paper orvery thin film) from undesirable curling down and around roller 312,between the top of guide 304 and the top of the static block 398 acrossthe rollers. A deliberate gap is shown on FIG. 12A (between the bottomof guide 304 and the machine base), so that if paper does curl, it has away out. The wire keeper also can be used on a machine according to FIG.1, and provides especial advantages there because there is no exit gapon the design of FIG. 1 for curling paper.

It will be appreciated that advantageous features mentioned above withregard to FIGS. 12A-12D, while particularly favorable for use indestroying paper (especially letter-width paper) also may be applied todestruction of other to-be-destroyed materials.

Thus, the present invention provides for high-security destruction ofvarious to-be-destroyed materials that are planar and relatively thin,with preferred examples being ordinary paper; key tape (e.g., paperalone; mylar alone; paper/mylar bonded together; paper/mylar/paperbonded together); photographs; film; transparencies; compact disks;credit cards, Smart Cards, cardboard; magnetic tape; diskettes, thinplywood; a whole cassette (preferably with the screws removed); etc.

While particular mention has been made of destruction of thin materials,and objects contacting thin materials, the invention also may be appliedto destroy thicker materials. When feeding a thicker material, thehorsepower of the cutter, the speed of the cutter, and/or the feederspeed is adjusted compared to a thin material. A single machine may beprovided that is adjustable for a range of various thicknesses andcompositions of materials to be destroyed.

Further favorable details for devices according to the invention are asfollows, understanding that the invention is not limited thereto. Thefollowing perfecting details may be appreciated with reference to aninventive embodiment such as the example shown in FIG. 1. Namely, theremay be included side plates on opposing sides of the pressure roller andthe friction feed capstan, the side plates retaining the pressure rollerand the friction feed capstan in a predetermined position. When such anarrangement is used, optionally each of the side plates may comprise aslot and opening; and the pressure roller may further include a rollershaft with the roller freely rotating thereabout, the roller shaft beingcaptured by the each slot of the side plates. There may further beincluded pressure screws insertable within each slot for adjusting adownward pressure on the pressure roller against the friction feedcapstan. There may further be included spacers which, in combinationwith the pressure screws, provide an adjustable deflection ofrubber-like material of the pressure roller against the friction feedcapstan. The deflection determination is fixed by design (thickness ofthe spacers), but relieves the operator from making any routine pressureadjustment. This provides a significant operational advantage ofsimplicity.

When side plates are used, the opening of each of the side plates mayallow the roller shaft to be removed from between the side plates inorder to quickly and easily remove the pressure roller. Also, when sideplates are used, there may be included a first screw positionable withinthe vertical slot of the first side plate and contacting a first end ofthe roller shaft in a first position; and a second screw positionablewithin the vertical slot of the second side plate and being able tocontact a second end of the roller shaft in the first position. Theremay be included first and second spacers positionable with respect tothe first and second opposing side plates, respectively. It may beconfigured wherein the first and second spacers in combination with thefirst and second screws provide an adjustment deflection of rubber-likematerial of the roller mechanism against the driven capstan. Thedeflection determination is fixed by design (thickness of the spacers),but relieves the operator from making any routine pressure adjustment.This provides a significant operational advantage of simplicity.

The metering mechanism may provide positive control of feed of theto-be-destroyed material as established by the capstan rotation. Inadditional embodiments, a positively controlled feeding mechanism may beprovided, such as one in which the feeding mechanism includes a firstand a second side plate, both having a vertical slot and an opening.Additionally, a driven capstan mechanism may be positioned between thefirst side plate and the second side plate. A roller mechanism having aroller shaft also may be provided. The roller shaft may be capturedwithin the vertical slot of the first side plate and the vertical slotof the second opposing side plate. The roller shaft further may bepositionable relative to the opening of the first side plate and theopening of the second side plate for removal therefrom. In embodiments,a first and a second screw are positionable within the respectivevertical slots of the first and second side plates. Spacers may also beprovided. The spacers, in combination with the screws, provide anadjustable deflection of rubber-like material of the roller mechanismagainst the driven capstan. The deflection determination is fixed bydesign (thickness of the spacers), but relieves the operator from makingany routine pressure adjustment. This provides a significant operationaladvantage of simplicity.

There may be included a pressure plate in contact with the sacrificialblade or round bar, the pressure plate substantially preventingvibrations caused by interactions of the rotary cutter and thesacrificial blade or round bar. There may be included a spring plungercontacting the pressure plate, the spring plunger forcing the pressureplate against the sacrificial plate or round bar.

There may be included a guide mechanism upstream from the meteringmechanism, the guide mechanism being in line with the metering mechanismand providing a guide for the to-be-destroyed material to be fed intothe metering mechanism.

While FIGS. 1 and 3 for simplicity and as a preferred embodiment showdestruction devices each using a single sacrificial material, it will beappreciated that the invention also includes using sacrificial materialin two or more locations. FIG. 9 is only one example of using sacrificematerial at more than one location. In FIG. 9, a to-be-destroyedmaterial M is being fed towards a rotating cutter 118 provided within arelatively-tightly cowled housing. As in FIG. 1, a sacrifice blade 120is disposed for contact with the rotating cutter. Additionally, a secondsacrifice blade 120′ is disposed at another location for similar contactwith the rotating cutter, for providing a second zero-clearance cuttingzone. Each of sacrifice blades 120 and 120′ could be replaced by a roundbar material appropriately arranged.

In the invention, the shape of a to-be-destroyed material may begenerally regular (such as generally planar (such as a sheet of paper,photograph, etc.), etc.), or may be irregular (such as cut, torn,wrinkled, bunched, etc.), so long as the to-be-destroyed material issuitably disposed in a cutting system including at least one sacrificialmaterial.

The invention not only provides zero-clearance cutting systems andmethods, but, such zero-clearance cutting systems and methods aremaintainable. For example, maintainable zero-clearance cutting of thepresent invention provides on the order of millions of cuts with thesame configuration of sacrifice blade and cutting edge without changingthe sacrifice blade or cutter.

Above, a secondary shredder has been mentioned. Further perfectingdetails regarding a secondary shredder are as follows. The secondaryshredder may include a single shaft common to the rotating secondaryshredder and the rotating primary cutter. Such a use of a common shaftprovides advantages of simplicity, low cost, ease of manufacturing, andreduced number of parts. The secondary shredder may be an extension ofthe primary cutter, with no change in basic cutter geometry from theprimary cutter. The cutter may be grooved to accommodate a stator. Onthe secondary shredder may be created a very large number of individualcutting stations (such as 600 to 800 cutting stations in a cylindricalenvelope of 1.3″ diameter×1.3″ long). Converting a radial cutting actioninto an axial cutting action may be provided. The helix of the basiccutter may be exploited to block straight-through passage of a particlethrough the secondary shredder, thus guaranteeing multiple cuts. A verylarge number of cutters may be provided in a very small space. Thegeometry of the stator walls may be kept extremely simple (such asstraight-through common-axis holes through all of the stator walls). Thestator may itself be simple and easy to attach (such as a split housingwhich simply clamps over the cutter). There may be provided a verysimple means to clean, inspect, and maintain the secondary shredder, byremoving a few screws. There may be exploited the helical geometry (suchas the helical flutes) of the cutter and the secondary shredder section(or other suitable geometry) to “pump” air laterally towards thesecondary shredder and the residue vacuum port and/or to “pump”already-cut particles laterally towards the secondary shredder and theresidue vacuum port. A vacuum may be used to enhance transport ofalready-cut particles laterally towards the secondary shredder section.A vacuum may be used to enhance transport of the particles out of themachine for collection.

Without the invention being in any way limited thereto, some examples ofusing the invention, in various embodiments, are mentioned as follows.

EXAMPLE 1

A prototype machine was built, Model KD-100 (Key Tape Disintegrator),one instance of the more general class of machines which the presentinventor calls “Micro-Disintegrators”. This class of machines is sonamed for two principle reasons: 1) Because the machines are physicallysmall, considering their function, 2) The output (or “residue”, as it isdesignated in the art) produced by such machines is composed ofextremely small dust-like particles, similar to those from adisintegrator, but finer. The actual KD-100 resembles that depicted inFIG. 1.

It utilizes only a single motor which performs all four of thesefunctions: a) drives the cutter; b) drives the vacuum dust collectionsystem; c) drives the positively-controlled material capstan feed(through gear trains); d), drives the extremely slow and gradual upwardsmotion of the sacrifice plate (through an additional gear train). Theactual machine is in full compliance with Department of Defense (DOD)requirements lists, meeting or exceeding all “must-have” requirementsand meeting or exceeding all “desirable” requirements, specifically forthe destruction of Key Tape. In this (KD-100) machine, the cutter ismade from high-speed steel, and (optionally) a solid-carbide cutter isavailable, with a life of 2-to-10 times that of high-speed steel.

The KD-100 uses ordinary 1/16″ or 3/32″ thick soft aluminum for itssacrifice blade. The model KD-100 machine destroys materials made ofpaper; made of a blend of plastics (such as polyester) and paper; andmade from polyester (or other thin plastics) alone, more completely thanby shredding alone, leaving no useable or recoverable information,reducing such materials to dust-like particles. The model KD-100 machineprovides extremely high security, because it reduces the information toan absolutely information-unrecoverable form, i.e., dust. The modelKD-100 machine is fast—it declassifies a 10″ strip of Key Tape to dustin about 4 seconds (very desirable in the event that an emergencyrequires rapid data destruction). The model KD-100 machine is easy andsafe to use, requiring no special operator skill, even under conditionsof high operator stress. There are no doors or drawers to open; nobuttons to push; no latches, catches, levers or hasps to operate. Thereare no exposed moving parts. The model KD-100 machine is simply switchedon, and the Key Tape is inserted. The feed system automatically capturesthe Tape, and feeds it to the cutting system. Switch off when done. Themodel KD-100 machine is low in cost, because it is physically small,light in weight, mechanically simple, and uses a minimum of moving partsto perform its function. The model KD-100 machine consumes very littleenergy to perform its function (typically under 300 watts) and is thuspractical to use with a small and low-cost back-up battery system. Themodel KD-100 machine is rugged due to its simplicity of design and therobust character of its components and attachments. For example, it usesa heavy-duty NEMA 4× fiberglass sculpted, gasketed enclosure. The modelKD-100 machine is relatively quiet (75 dBA, measured at the operator'sear), for an unobtrusive operation in an office environment. The modelKD-100 machine is friendly to the environment, because it merely cutsmaterial, producing no high temperatures, airborne dust, smoke, toxicfumes, or residue. It simply makes a cool, harmless powder. The modelKD-100 machine is easy to maintain because of its basic simplicity,small number of moving parts, and quick-release mechanisms. Examples:Cutter replacement, along with cutter bearings (done in one operation)takes under 10 minutes. In an additional 2 minutes, the sacrifice bladecan be replaced. Motor replacement can be performed in about 5 minutes.Rubber roller replacement can be performed in under 1 minute. These arethe only parts that one might normally need to replace to due normalwear and tear. No lubrication required. Requires no special tools to fixor adjust it. The model KD-100 machine provides the possibility ofalmost-silent covert operation (by reducing speed). The model KD-100machine allows for emergency high-volume operation as follows: a) snapopen the lid; b) remove the bag; c) insert an exhaust tube; d) operate.The model KD-100 machine contemplates and allows for the possibility ofpower loss: the tape can just be pulled out. The model KD-100 machine iscompact, having a size of 8×10×6½″ (h) (i.e., 205×255×65 mm). The modelKD-100 machine is light, weighing 9.1 lbs. (4.1 kg). The model KD-100machine is a desk-top design, by virtue of this small, light-weightsize. The model KD-100 suits a right-handed or left-handed operatorsimply by rotating the entire machine 90 degrees to suit. The modelKD-100 machine provides superior residue processing and disposal using alow-cost disposable filter bag, which is quickly and easily changed. TheKD-100 machine destroys materials made of paper; made of a blend ofplastics (such as polyester) and paper; and made from polyester (orother thin plastics) alone, more completely than by shredding alone,leaving no useable or recoverable information, reducing such materialsto dust-like particles.

EXAMPLE 2 Round-bar Sacrifice Material

In this example there is assumed a round sacrifice bar ⅜″ diameter, or1.17″ circumference. A full revolution of the bar would present 1.178million micro-inches to the cutter. At about 13 ft/minute, the sacrificefeed would be 30×13 (or 390) micro-inches circumferentially per minute,which works out to 390/1,178,000 (or 0.000331) sacrifice bar revolutionsper minute, or 0.0198 (or 1/50.34) sacrifice bar revolutions per hour.The bar will last about 50 hours, or 46,800 feet. In this case, a feedrate of approximately 30 micro-inches of sacrifice material per footlength of destroyed material, or about 400,000 inches of destroyedmaterial per inch of sacrifice material is provided, for this round-barsacrifice material example.

This may be compared to about 0.500 sacrifice JACKSCREW revolutions perHOUR in a sacrifice PLATE embodiment. Correspondingly, more worm-geardrive ratio reductions are needed to operate with the round bar.

EXAMPLE 3 DocuStroyer Paper-destruction Machine

A destruction machine for to-be-destroyed 8½ inch-wide paper wasconstructed according to FIGS. 12A-12D. A cutter was made from cobaltsteel, coated with titanium nitrate (to enhance its hardness). A cutteras in FIG. 11 was used. The cutter had raised cutting edges withvertical serrations, with a 0.007 inch offset pattern to the serrations.A 9-inch wide sacrifice material of 3/16 inch thick soft aluminum wasused. A destruction machine for 8½ inch wide paper was constructed asdescribed above with regard to FIGS. 11-12D.

The inventive DocuStroyer machine was tested on 10 paper pages in rapidsequence, fed one at a time (generating 10 end-strips). The end-of-pagestrip processed through the secondary shredder. All that remained of the10 paper pages was powdery dust.

In addition to the excellent destruction capability provided by theDocuStroyer device of this example, the inventive machine has mechanicaladvantages over conventional paper-destruction machines.

Number of rotating cutter parts Inventive Example 3 1 Conventionalcommercial 6 3-head paper destruction machines

Examples 1-3 reflect cutting systems have been accomplished which arecapable of cutting a material such as, for example, tape or paper, intoa fiber or powder. In these examples using a rotary cutter and arelatively-softer sacrifice material, the contacting portion wasobserved to have zero clearance during the cutting operation. Zeroclearance during the cutting operation enhanced the ability to destroythe material. Also, destruction of material was further enhanced byadvantageous strategic patterning of cutting edges on a rotary cutter(such as applying an offset to the cutting edge pattern), and further bysecondary shredding features (such as the secondary shredder of Example3 and FIGS. 12C-12D). The invention was observed in the testing ofExamples 1-3 above to provide systems for reducing to-be-destroyed paperand other relatively-thin planar materials to a dust or powder-size.

EXAMPLE 4 Maintainability of Zero-clearance Cutting

For a paper destruction machine according to Example 3, in which asacrifice blade is used with the cutter of Example 3, maintainability iscalculated as follows, where operation of the cutter is at 15,000 rpm,with 24 cuts per cutter revolution. 2500 feet of paper are processed at4 seconds/foot, which is 10,000 seconds which is 166 minutes ofoperation. 166 minutes of operation multiplied by 15,000 rpm is 2.49million revolutions. 2.49 million cutter revolutions multiplied by 24zero-clearance cuts per revolution is 59.76 million zero-clearance cuts.

After 59.76 million zero-clearance cuts of paper (which is veryabrasive), the cutting blade is expected to then be dulled by the paper(rather than dulled by interaction with an object other than that beingcut). The sacrifice material is relatively unspent, and may still havemiles to go (enough material remaining for another 30,000 feet of keytape). From these calculations, the advantage is seen of how very manyprecision zero-clearance cuts may be provided without the cutter beingdulled. For conventional zero-clearance cutting, it would not bepossible to provide millions or tens of millions of cuts without bladedulling.

EXAMPLE 5 Reciprocal Cutter Systems

Another example of usage of a sacrifice material is with a reciprocalcutter system, such as a reciprocal cutter system in which a sacrificialblade is used with a shearing blade (such as, for example, in FIG. 7) ora round sacrifice material is used with a shearing blade (such as, forexample, in FIG. 8). In the reciprocal cutter system of FIGS. 7 and 8, atight fitting guide 701 is shown. A blade (such as a steel blade) goesup and down.

In FIG. 7, a sacrificial blade or bar or plate 720 (constrained by itsown tight-fitting guide) is very slowly advanced towards a shearingblade 702 (such as a steel reciprocating shearing blade). The sacrificematerial slowly advances to the point of cutting. The arrangement ofFIG. 7 is particularly suited for thin materials.

In FIG. 8, a round sacrifice material 820 is used with a shearing blade702. To-be-cut material M is fed on a tangent to the rotating sacrificematerial 820. The rotation of the sacrifice material 820 is extremelyslow. (The diagonal feeding of to-be-cut material M shown in FIGS. 7 and8 also may be used in other embodiments of the invention and is notrestricted to embodiments in which a reciprocal cutter is used.)

EXAMPLE 6

Referring to the inventive example depicted in FIGS. 11-12, if there are10 holes in each wall, and 6 cutter flutes, and 10 wall edges, then asingle revolution of the cutter results in 600 shearing operations. Ifan 8-flute cutter is used, then a single revolution of the cutterresults in 800 shearing operations. The inventive example depicted(FIGS. 11-12) is so configured, and has been built and testedsuccessfully with both 6-flute and 8-flute cutters. Even at a relativelyslow cutter speed of 1,500 RPM, there would be 0.9 to 1.2 millionshearing operations/minute (Or 15,000 to 20,000 shearing operations/PERSECOND). The inventive example depicted (FIGS. 11-12) has beensuccessfully tested at 4 times this speed. Those conversant in the artcan easily see that no particle could pass through the SecondaryShredder's blizzard of cuts without being reduced almost to dust. Infact, a large percentage of this machine's output actually is dust.

While the invention has been described in terms of preferredembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theappended claims.

1. A zero clearance cutting apparatus, comprising: at least one cutter;and positively-controlled material feed mechanism for controlling afeeding rate of material to be destroyed; and at least one sacrificialround bar abutting a portion of the at least one cutter during arotation of the at least one cutter, the sacrificial round bar beingrelatively softer than the cutter; wherein output is a security-levelfine material.
 2. The zero clearance cutting apparatus of claim 1,wherein the at least one cutter is a rotary cutter.
 3. The zeroclearance cutting apparatus of claim 1, wherein thepositively-controlled material feed mechanism controls particle size ofthe material being destroyed by controlling both (a) the feed rate ofthe material entering between the at least one sacrificial round bar andthe at least one cutter and (b) the rotational speed of the at least onecutter.
 4. The zero clearance cutting apparatus of claim 1, wherein anoutput is one of an information-unrecoverable product or a shreddedproduct, and a disintegrated product.
 5. The apparatus of claim 1,wherein the cutter is cowled.
 6. The cutting system of claim 5, furtherincluding a secondary cowling.
 7. The apparatus of claim 1, including ahelical cutter, wherein the cutter has a helical shape that blocksstraight-through passage of a particle.
 8. The apparatus of claim 7,wherein the helical cutter is a secondary shredder that cuts after aprimary cutting system including a sacrifice material has operated on ato-be-cut material.
 9. The apparatus of claim 8, wherein multiple cutsof a material passing through are provided by the secondary shredder.10. The apparatus of claim 8, wherein a number of cutters in a smallspace is maximized.
 11. The apparatus of claim 8, further includingstator walls having a simple geometry.
 12. The apparatus of claim 11,including straight-through common-axis holes through all of the statorwalls.
 13. The apparatus of claim 11, including a simple, easilyattached stator.
 14. The apparatus of claim 13, including a splithousing which simply clamps over the secondary shredder.
 15. Theapparatus of claim 8, wherein (a) air is pumped laterally towards thesecondary shredder and the residue vacuum port and/or (b) already-cutparticles are pumped laterally towards the secondary shredder and theresidue vacuum port.
 16. The apparatus of claim 8, wherein a vacuumenhances transport of already-cut particles laterally towards thesecondary shredder.
 17. The apparatus of claim 8, includingvacuum-enhanced transport of cut particles for collection.
 18. A cuttingmechanism for cutting a material, comprising: a metering mechanism formetering the material at a predetermined, positively controlled rate; atleast one rotary cutter positioned downstream from the meteringmechanism; and at least one sacrificial round bar which just barelycontacts a portion of the rotary cutter during a phase of rotation ofthe rotary cutter, the contacting portion being a zero clearance portionbetween a portion of the rotary cutter and the sacrificial round bar,wherein the material is metered to the zero clearance portion by themetering mechanism for disintegrating the material into a fiber orpowder form.
 19. The cutting mechanism of claim 18, wherein the rotarycutter is made from a first material and the sacrificial round bar ismade from a second material which is softer than the first material. 20.The cutting mechanism of claim 18, wherein the sacrificial round barincludes an edge which conforms to a shape of the path of the rotarycutter at the contacting portion.
 21. The cutting mechanism of claim 20,wherein the edge is arc shaped.
 22. The cutting mechanism of claim 18,further comprising a mechanism for incrementally moving the sacrificialround bar into contact with the rotary cutter as the sacrificial roundbar wears down.
 23. The cutting mechanism of claim 22, wherein theincrementally moving mechanism is a rotating jackscrew mechanism coupledto the sacrificial round bar.
 24. The cutting mechanism of claim 23,wherein the jackscrew mechanism system includes an outward extendingtapped-through plate whose tapped-through hole engages the jackscrewwhich is adapted to lift the sacrificial round bar into Contact with therotary cutter.
 25. The cutting mechanism of claim 22, further comprisinga motor for driving the rotary cutter, the metering mechanism, therotation of the jackscrew, and driving a dust-collection vacuum.
 26. Thecutting mechanism of claim 25, further comprising a gear reductionsystem between the motor and the jackscrew.
 27. The cutting mechanism ofclaim 18, wherein the metering mechanism includes a pressure roller anda friction feed capstan.
 28. The cutting mechanism of claim 27, furthercomprising side plates on opposing sides of the pressure roller and thefriction feed capstan, the side plates retaining the pressure roller andthe friction feed capstan in a predetermined position.
 29. The cuttingmechanism of claim 28, wherein: each of the side plates comprise a slotand opening; and the pressure roller further includes a roller shaftwhich the roller freely rotates thereabout, the roller shaft beingcaptured by each slot of the side plates.
 30. The cutting mechanism ofclaim 29, further comprising pressure screws insertable within each slotfor adjusting a downward pressure on the pressure roller against thefriction feed capstan.
 31. The cutting mechanism of claim 30, furtherincluding spacers which, in combination with the pressure screws,provide an adjustable deflection of rubber-like material of the pressureroller against the friction feed capstan.
 32. The cutting mechanism ofclaim 28, wherein the opening of each of the side plates allow theroller shaft to be removed from between the side plates in order toremove the pressure roller.
 33. The cutting mechanism of claim 18,wherein the metering mechanism provides positive control of feed of thematerial as established by capstan rotation.
 34. The cutting mechanismof claim 18, further comprising a pressure plate in contact with thesacrificial round bar, the pressure plate substantially preventingvibrations caused by one of the rotary cutter and the sacrificial roundbar.
 35. The cutting mechanism of claim 34, further comprising a springplunger contacting the pressure plate, the spring plunger forcing thepressure plate against the sacrificial round bar.
 36. The cuttingmechanism of claim 18, further comprising a guide mechanism upstreamfrom the metering mechanism, the guide mechanism being in line with themetering mechanism and providing a guide for the material to be fed intothe metering mechanism.
 37. The cutting mechanism of claim 18, whereinat least one tooth of the rotary cutter grabs the material prior to thematerial being metered into the zero clearance portion.
 38. The cuttingmechanism of claim 37, wherein the combination of the rotary cutter andthe sacrificial round bar cuts the material into the fiber or powderform.
 39. A cutting mechanism, comprising: a positively controlledfeeding mechanism; and a cutting mechanism having a zero clearanceportion, the cutting mechanism including: at least one cutting bladedisposed concentrically about a shaft; and at least one rotatablesacrificial rod having an initial cutout portion, the zero clearanceportion being disposed between at least a cutting portion of the cuttingblade and the rotatable sacrificial rod.
 40. A method of destroyingpolyester material, comprising the steps of: feeding the polyestermaterial at a predetermined positively controlled rate towards a zeroclearance portion formed between at least one cutter and at least onesacrificial blade or round bar, grabbing the polyester material with atooth of the cutter; pulling the polyester material into the zeroclearance portion with the tooth of the cutter; and disposing thepolyester material at the zero clearance portion.
 41. The method ofclaim 40, wherein the disposing step shreds the polyester material intoan information-unrecoverable form.
 42. The method of claim 41, whereinthe feeding step is incremental.
 43. The method of claim 41, wherein thefeeding step is at a rate of approximately 30 millionths of an inch ofsacrificial blade material per foot length of destroyed material.
 44. Amethod of destroying paper, comprising the steps of: feeding the paperat a predetermined positively controlled rate towards a zero clearanceportion formed between at least one cutter and at least one sacrificialblade or round bar; grabbing the paper with a tooth of the cutter;pulling the paper into the zero clearance portion with the tooth of thecutter; and disposing the paper between the cutter and the sacrificialblade or round bar at the zero clearance portion; wherein the disposingstep shreds the paper into an information-unrecoverable form.
 45. Themethod of claim 44, wherein the feeding step is at a rate ofapproximately 30 millionths of an inch of sacrifice material per footlength of destroyed material.
 46. A method of destroying material,comprising the steps of: feeding the material at a predeterminedpositively controlled rate towards a zero clearance portion formedbetween at least one cutter and at least one sacrificial blade or roundbar; grabbing the material with a tooth of the cutter; pulling thematernal into the zero clearance portion with the tooth of the cutter;and disposing the material between the cutter and the sacrificial bladeor round bar at the zero clearance portion; wherein the disposing stepshreds the material into an information-unrecoverable form.
 47. Themethod of claim 46, wherein the material is paper.
 48. The method ofclaim 46, wherein the material has been converted into a security-levelfine material.
 49. The method of claim 46, wherein the materialto-be-destroyed is planar and the method comprises: passing theto-be-destroyed planar material through a rotating cutter system,wherein the cutter includes a plurality of cutting edges thatrespectively take tiny nibbles out of the to-be-destroyed planarmaterial, with the axis about which the cutter rotates being parallel tothe to-be-destroyed planar material.
 50. The method of claim 49, whereinthe cutter rotates about a fixed axis of rotation.
 51. The method ofclaim 50, wherein the cutter rotation axis is itself generallynon-moving.
 52. The method of claim 49, including initial cutting of theto-be-destroyed material by at least one cutting edge of the rotatingcutter, followed by further cutting by at least one other cutting edgeof the rotating cutter.
 53. The method of claim 52, comprising multiplefurther cutting.
 54. The method of claim 49, wherein the cutting edgesof the rotating cutter are arranged in a strategic pattern.
 55. Thedestroying method of claim 46, including auger transportinginitially-cut to-be-destroyed material.
 56. The destroying method ofclaim 46, including selecting one or more of the following: a materialof a cutting edge, a size of a cutting edge or edges, a pattern of aplurality of cutting edges, a manner of movement of the cutting edge oredges, a shape of the sacrificial material, a disposition and/ormovement of the sacrificial material, and/or a feed of thematerial-to-be-cut.
 57. The destroying method of claim 46, wherein acompact disk is cut into high-security fine pieces.
 58. The destroyingmethod of claim 46, wherein magnetic tape is cut into high-security finepieces.
 59. The destroying method of claim 46, wherein a laminateddata-bearing card is cut into high-security fine pieces.
 60. Thedestroying method of claim 46, wherein a credit card or bank card is cutinto high-security fine pieces.
 61. The destroying method of claim 46,wherein stored data is cut into high-security fine pieces.